Continuous casting plant for slabs

ABSTRACT

A continuous casting plant for the production of slabs, comprising a straight, vertical mould which is water-cooled and releasably mounted in a frame, a secondary cooling or bar guiding means arranged below said mould and including a vertical part with a bending zone which is adapted to be lifted in and out in vertical direction through the frame after the mould has been lifted out of the frame, and a curved part which is adapted to be displaced in horizontal direction, and means for drawing and bending said bar, which are designed as a combined pulling, straightening and rolling stand adapted to be displaced in and out as an individual constructional unit. This plant affords the advantages of a low construction height, and of high operational safety. The quality of the products is improved because the occurrence of cracks is avoided and the bar may solidify symmetrically. Furthermore this plant may be built into existing steel works.

United States Patent [191 Schoffmann et al.

[451 May 14,1974

1 1 -CONTINUOUS CASTING PLANT FOR SLABS [75] lnventors: Rudolf Schoffmann; Rudolf Rinesch,

both of Linz, Austria [73] Assignee: Vereinigte Osterreichische Eisen-und Stahlwerke Aktiengesellschaft, Linz, Austria [22] Filed: July 28, 1972 [21] Appl. No.: 276,099

Related U.S. Application Data [63] Continuation of Ser. No. 39,479, May 21, I970,

abandoned.

30] Foreign Application Priority Data 7 May 30, I969 Australia .5l93 I V [52] U.S. Cl 164/260, 164/282, 164/283 [51] Int. Cl. 822d 11/12 [58] Field Of Search... 164/282, 283, 260

[56] References Cited :UNlTED STATES PATENTS 3.627.026 12/1971 8011116 8181 164/282 3,495,651 2/1970 ROkOP et 81. 164/282 X, FOREIGN PATENTS OR APPLICATIONS 407,422 8/l966 Switzerland 164/282 Primary ExaminerRobert D. Baldwin Attorney, Agent, or FirmBrumbaugh, Graves, Donohue & Raymond [57] ABSTRACT A continuous casting plant for the production of slabs,

comprising a straight, vertical mould which is water-- cooled and releasably mounted in a frame, a secondary cooling or bar guiding means arranged below said mould and including a vertical part with a bending zone which is adapted to be lifted in and out in vertical direction through the frame after the mould has been lifted out of the frame, and a curved part which is adapted to be displaced in horizontal direction, and means for drawing and bending said bar, which are designed as a combined pulling, straightening and rolling stand adapted to be displaced in and out as an individual constructional unit. This plant affords the advantages of a low construction height, and of high operational safety. The quality of the products is improved because the occurrence of cracks is avoided and the bar may solidify symmetrically. Furthermore this plant may be built into existing steel works.

2 Claims, 1 Drawing Figure 5' 17 i l l PATENTEDIAYMISM 3.810.507

II VENTORS RUDOLF SCHOFFMAN N 8 BY RUDOLF RINESCH .afwxwgwlmw' their Arm/wars.

, curve-type plants.

CONTINUOUS CASTING PLANT FOR SLABS This is a continuation, of application Ser. No. 39,479 filed May 21, 1970, now abandoned.

The invention relates to a continuous casting plant for slabs comprising a straight, vertical mould which is mounted in frame and water-cooled, secondary cooling or bar guiding means arranged below said mould and adapted to be lifted in and out and including a vertical part with a bending zone and a curved part, and means for drawing and bending the bar.

There are various difiiculties in casting to slabs which are about 1,000 to 2,000 mm broad and about 140 to 250 mm thick, which difficulties are due primarily to the construction of the plants and to metallurgical factors. Vertical plants in which the bar leaves the mould vertically in downward direction and is vertically passed on and shom to length in vertical position after its solidification have a great construction height, as a rule they cannot be built into existing steel works and they are very expensive. It has, therefore, been proposed to employ plants with a curved mould and a postpositioned curved bar guide soas to reduce the construction height of the plants and to permit a horizontal delivery of the solidified bar. However, it is difficult to manufacture curved moulds and, apart from that, they entail metallurgical disadvantages as the casting stream impairs the formation of the casting shell and a uniform and symmetrical solidification and segregation in the bar, respectively. In the production of billets and less sensitive steel qualities these difficulties have been partly eliminated but slabs of large dimensions can hardly be produced in a satisfactory manner in such In another type of continuous casting plant the bar leaves a vertical, straight mould, it is then further cooling in a comparatively long straight guiding section, at

tion into horizontal position. In such plants some of the metallurgical disadvantages present in the curved plant may be avoided but the costs for the construction are considerable and it is very difficult to build such plants into existing steel works.

In a further type of continuous casting plant the bar, on leaving a vertical mould, is guided through a relatively short, straight guiding section and bent in a bending zone in steps and progressively in a manner that no inadmissible stresses will occur at the surface of the bar. The bar then is further cooled in a curved guide at the end of which it is seized by a pulling stand and straightened. Although this embodiment avoids some of the metallurgical disadvantages of a curved plant, it does not guarantee and avoidance of cracks below the surface and in the vicinity of the solidification front.

The invention is aimed at creating a continuous casting plant for slabs in which the metallurgical disadvantages of known plants are avoided and which has a low construction height.

It is a further aim of the invention to construct the plant by employing pre-fabricated construction units or elements which may easily be exchanged.

In a known construction the secondary cooling zone or bar guiding means, respectively, is mounted to be rotatable; for moving it out the means merely has to be swung and driven out. However, the construction is not suitable for great plants in which the bar guiding means has to be made of several individual parts. It would be far'too expensive to provide for each individual part to be rotatable and capable of being driven out so that such aconstruction would hardly be feasible.

Further aims of the invention are to create a plant moved in and out as an individual constructional unit.

An important feature of the plant lies in that the vertical distance between the casting level in the mould and the bottom end of the vertical part of the bar guiding means amounts to from 1.0 to 4.0 m.

The ast part of the curved bar guiding means may be designed as non-heated equalization zone.

In order that the invention may be more fully understood these and further features of the invention are explained in greater detail in the following description in connection with the schematical drawing.

A water-cooled, straight mould l is mounted in a frame 2. Between the frame 2 and the mould 1 there are several rapid connections for the cooling water and forfixing the mould to the frame 2, which, however, are not shown in the drawing. The frame 2 is connected with a mould drive 32 which serves to oscillate the frame 2 and the mould l in vertical direction. Two pairs of rolls are fixed to and oscillate together with the mould. The vertical, straight bar guiding part 3 comprising a bearing stand 5 with built in rolls 4 is arranged below the mould 1. At its lower end, in the area of the last pairs of rolls 4, a transitional or bending zone 6 is .penetrating casting stream is prevented from damaging the casting shell and the bar solidifies in a uniform manner. 4

When forming the bending zone 6 care has to be taken that at no place of the already partly solidified bar impermissible extensions will occur in any phase of the deflection. At the border line between liquid and solidified layers any elongation should not amount to more than 0.2 to about 0.7 percent, in dependence on the steel quality. In this transitional area the temperature amounts to about 1,400C. With increasing distance from the solidification front or with falling temperature, respectively, the permissible elongation increases greatly. Thus, the bar is continuously bent in the bending zone 6, i. e., not in steps, and so slowly that no cracks may occur in the bar.

According to the invention the straight bar guiding part 3 with the bending zone 6 is formed as an individual, compact constructional unit. It may be lifted out in upward direction after the mould has been lifted out from the frame. in the drawing the lifted off mould is shown in broken lines and denoted with-numeral 1'. The drawing also illustrates in broken lines the bar guiding part 3' after it has been lifted out through the frame. The curved bar guiding part 7 is equally formed as an independent constructional unit. It comprises a curved bearing stand 9 with rolls 8 which may have dif ferent diameters, and wheels 10, 10' for displacing the entire constructional unit in horizontal direction on rails 16, 17. The secondary cooling zone extends from the mould to the end of the bar guide 7. It contains supply ducts and spray jets for the cooling water. This bar guiding means comprising two parts is followed by a means for drawing the bar, which means is designed as combined pulling, straightening and rolling stand 12 and comprises a pair of rolls 13, a pair of rolls 14 for straightening the bar and a guiding roll 15. The pair of rolls 13 serves to exert pressure on the bar sufficient to reduce the bar by up to 30 percent. If desired, also the straightening pair of rolls 14 may be used to exert presstraightening and rolling stand where it is shaped by 7- to 20 percent; in this shapingprocess it is primarily the core zone of the, bar that becomes worked. The bar core has an essentially higher temperature, e. g., a temperature that is higher than 900C, preferably a temperature of 1,200 to l,300C. The marginal zone or the surface of the bar 11, however, has a temperature in f the range of about 800 to about l,0OOC. If such a bar is subjected to shaping, the core zone of the bar undergoes a substantially higher degree of working than the marginal zone." Thus, when the bar 11 is shaped in the combined pulling, straightening and rolling stand 12 which is arranged after the curved bar guide 7 the core of the bar is densified; this affords a qualitative advantage which becomes particularly obvious when the bar is subjected to further rolling in a conventional second I rolling plant to obtain plates. in the second rolling process it is primarily the marginal zonethat is shaped so that a final product is obtained that is evenly shaped over its entire cross section.

After shaping of the bar 11 by means of the rolls 13, the shaped bar 11' is directed to be parallel to the mill floor 18 by means of the straightening rolls 14. it is also possible to permit the cast bars to run through the stand 12 without shaping of their cross sections in which case the rolls 13 function only as pulling rolls.

It is also possible to pass the bar through a nonheated equalization zone so that the bar enters into the combined pulling, straightening and rolling stand with a temperature that is highly uniform over its cross section and is shaped by about 10 to 20 percent. Such a non-heated equalization zone 21 arranged as the last part of the curved bar guide 20 is shown in the left part of the drawing. After the temperature has equalized it is primarily the marginal zone of the bar that becomes shaped. This is of great advantage with bars made of rimming steel which have a bubble wreath in their interior below the surface. This bubble wreath would have a heat insulating effect when the bar is re-heated 'part of the secondary cooling zone a constructional unit 19, which, likewise, is horizontally displaceable andmay easily and quickly be exchanged for the bar guide 7 which is in position for operation. The equalization zone may also be designed as a separate constructional unit between the bar guide 7 and the pulling, straightening and rolling stand.

The plant may also be provided with a means for the flying exchange of the distributors andthe ladles; this means comprises columns 22, which penetrate the pouring platform 23, and horizontally rotatable arms 24, 25 for two ladles and two rotatable arms 26, 27 for two distributors; of these, one ladle 28 and one distributor 30 are always outside the area of the mould l as in the position shown. In working position a second ladle which is not shown is positioned by means of the rotatable arm 25 above a seocnd tundish held by the rotatable'arm 27. Numeral 29 denotes the bearing trunnions of the ladle 28. In addition, the tundishes may be vertically displaceable along the column 22, so that the drains of the tundishes which, however, are not shown in the drawing may be immersed below the casting level in the mould 1.

What we claim is:

l. A low-head continuous casting plant for the production of slabs preferably having a width of at least I 1,000 mm from a continuously cast steel bar, comprising a frame,

a straight, vertically-oriented mould releasably mounted in the frame and being liquid-cooled, driving means attached to the frame and mould for oscillating said frame and said mould,

a first secondary cooling and bar guiding means positioned below the mould and comprising a straight vertical upper section and a curved lower section integral with the upper section for bending the bar I having a liquid core and being of such configuration as. to provide for continuous bending of the bar, said first secondary cooling and bar guiding means being of such a size to be vertically removable through the frame and arranged below the mould in a manner that the vertical distance between the casting level in the mould and the downstream end of the straight vertical upper section is in the range from 1.0 to 4.0 meters,

a second'secondary cooling and bar guiding means positioned downstream from said first secondary cooling and bar guiding means and being substantially are shaped,

means for horizontally displacing the second secondary cooling and bar guiding means, and

means positioned downstream of the second secon' dary cooling and bar guiding means for drawing the bar through the first and second secondary cooling and bar guidingmeans and for straightening and drawing out the bar in horizontal direction.

2. The plant as defined in claim 1 wherein the second secondary cooling and bar guiding means comprises a first liquid-cooled section and a second non-heated equalization section.

CERTIFICATE OF CORRECTION Patent No. 3,810,507 Dated May 1 197 i Inventofls) SchBffmann et al.

It: is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

First page, Item [30], "Australia" should be --Austria--.

Col. 1, line ll, after "casting" insert --stee1--; lines 35 and 36, "cooling" should read "cooled"; line 39 "horizontl" should read el-whorizontaha ,line. .55, "and" should read --the--;

Col. '2, line 2%, "ast" should read --last--- line 43, after 5 "over" insert -to--.

Col. line 19, "second" should read -second--.

Signed'and sealed this 5th day of November 1974.

LSBAL) fittest:

, c. MARSHALLlDANN ICCOY M GIBSON JR. Commissioner of Patents \ttesting Offic 

1. A low-head continuous casting plant for the production of slabs preferably having a width of at least 1,000 mm from a continuously cast steel bar, comprising a frame, a straight, vertically-oriented mould releasably mounted in the frame and being liquid-cooled, driving means attached to the frame and mould for oscillating said frame and said mould, a first secondary cooling and bar guiding means positioned below the mould and comprising a straight vertical upper section and a curved lower section integral with the upper section for bending the bar having a liquid core and being of such configuration as to provide for continuous bending of the bar, said first secondary cooling and bar guiding means being of such a size to be vertically removable through the frame and arranged below the mould in a manner that the vertical distance between the casting level in the mould and the downstream end of the straight vertical upper section is in the range from 1.0 to 4.0 meters, a second secondary cooling and bar guiding means positioned downstream from said first secondary cooling and bar guiding means and being substantially arc shaped, means for horizontally displacing the second secondary cooling and bar guiding means, and means positioned downstream of the second secondary cooling and bar guiding means for drawing the bar through the first and second secondary cooling and bar guiding means and for straightening and drawing out the bar in horizontal direction.
 2. The plant as defined in claim 1 wherein the second secondary cooling and bar guiding means comprises a first liquid-cooled section and a second non-heated equalization section. 